This invention relates generally to laminates of regenerated cellulose film and aluminum foil and more particularly to an improved laminate of such materials having a superior resistance to delamination.
Bonding of coated regenerated cellulose film to aluminum foil through the use of various adhesives is well known in the packaging industry. With such laminates the film used is a synthetic polymer coated cellulosic film, the coating usually being saran or some form of polyvinylidene chloride resin. The coated film is then laminated to the aluminum foil either with or without the application of an adhesive to assure the necessary bond between the two materials. The use of uncoated regenerated cellulose films in laminates with aluminum foil has generally not been attempted because of the difficulty in achieving a direct bond between cellulose film and aluminum foil, no matter what adhesive is used to bond the two together. When such uncoated cellulose film/aluminum foil laminates are later coated and employed in packaging and the package heat-sealed, the structure tends to delaminate because of failure of the adhesive bond between the plies of cellulose film and aluminum foil. Exact temperatures of the failure will depend upon the exposure time and to some degree on the pressures and other mechanical stresses to which the film is subjected during the sealing operation. In any event, it is common for delamination to occur and the conditions required for delamination are encountered in many packaging machines, severely limiting the applications in which uncoated cellulose film/aluminum foil laminated structures can be used.